docs: def set_font_face(self, font_face):
          """Replaces the current font face with :obj:`font_face`.
  
          :param font_face:
              A :class:`FontFace` object,
              or :obj:`None` to restore the default font.
  
          """
          font_face = font_face._pointer if font_face is not None else ffi.NULL
          cairo.cairo_set_font_face(self._pointer, font_face)
          self._check_status()